Helicoidal device for extracting material in particle form from a reservoir

ABSTRACT

An extraction device for extracting a material in particulate form from a reservoir includes an extraction member in the form of a helicoidal winding connected to a motor for driving it in rotation about its central axis. The helicoidal winding is driven so as to sweep it about an axis of sweep along the bottom of the reservoir and the winding may be curved at its distal end so as to sweep along the periphery of the reservoir. The winding may be enclosed within a tubular conduit and a section of the peripheral wall of the reservoir may be provided to cooperate with the helical winding.

TECHNICAL DOMAIN

The invention relates to a device for extracting a material in particleform, i.e. pulverulent or granular, from a reservoir, particularly asilo.

The technical domain concerned is that of the mechanical extraction ofsuch materials from an extraction member of helicoidal type.

PRIOR ART

The prior art knows two families of such extraction members.

The first family relates to devices comprising at least one rigid screwdisposed, at least partially, parallel to the bottom or to the base of areservoir. The screw is animated by a movement of rotation on itself andby an angular sweeping displacement about an axis, generallyperpendicular to the plane of the bottom or the base.

Extraction is effected by entrainment and evacuation of the product inthe direction of an outlet occupying, most often, the center of thebottom.

The devices of this family do not give entire satisfaction for differentreasons. They are generally expensive to buy and maintain and representcumbersome structures. The screw constitutes a rigid member comprising acore, of appreciable section, constituting a brake to the progression ofangular displacement within the mass of material. The rigid structure ofthe screw and its section require the application of a driving torque ofhigh value, as soon as rotation starts and, consequently, the employmentof expensive high-power motorization means. The means for supporting thescrew, necessarily employed, results in the screw being placed at adistance from the bottom or base of the reservoir. The screw is thusincapable of scraping a minimum layer of product which permanentlyremains on the bottom of the reservoir. Moreover, a rigid screw, due toits structure, does not make it possible to furnish variable dosagesbelow a determined minimum dosage.

The second family concerns devices comprising an extractor member in theform of a helicoidal filiform winding; a winding of a thin, rod-likeelement. The object of the invention specifically relates to the devicesof this second family.

The prior art furnishes several propositions for producing extractordevices relating to this second family.

One of them is taught by Patent FR 1 376 898 providing a storageenclosure comprising, at a distance from the bottom, a rectilinear,helicoidal, filiform winding occupying a fixed position and driven inrotation on its axis. Such a device presents the drawback of not beingable to be adapted to reservoirs of cylindrical shape, generallyretained for storing pulverulent or granular products or materials.Another drawback of this device resides in the impossibility ofextracting all the mass of products or materials from the reservoir, dueto the establishment and support of the winding at a distance from thebottom.

Another proposition has been made by Application EP-A-0 016 685providing to arrange a peripheral annular groove open in the flat bottomof a reservoir. A helicoidal filiform winding is housed in the groove inwhich it may be animated by a rotation on its axis by a driving memberfitted at one of its ends. The filiform winding according to thisteaching performs in fact only a function of take-up as the extractionproper is ensured by a scraper rotating in a plane parallel to thebottom of the reservoir.

Such a device employs two distinct scraping/extracting and drawing-offmeans requiring two means for driving in rotation and two monitoring andservocontrol systems. In addition, such a device has for a drawback toleave on the flat bottom of the reservoir a layer or cake of products ormaterials whose thickness is equal to the distance separating the bottomfrom the plane of rotation of the rotating scraper.

Application DE-A- 19 19 698 should also be mentioned, providingextending the truncated bottom of a reservoir by a bent conduit in whichis disposed a helicoidal filiform winding moved in rotation on its axis.The terminal part of the winding rises substantially vertically insidethe truncated bottom occupied by the product or material in particleform.

Such a device presents several drawbacks. The first consists in that itsuse cannot be envisaged for flat-bottomed reservoirs. The second residesin the inefficiency of extraction associated with such a proposition. Infact, shortly after setting in rotation, the terminal part of thefiliform winding makes itself, within the mass of pulverulent orgranular product, a housing inside which it is centered. The naturaltendency of the product to vaulting or autocompaction opposes collapseand, consequently, rotation of the terminal part is effected inside thehousing that it has created without effecting extraction.

STATEMENT OF THE INVENTION

The present invention has for its object a novel extraction device, ofthe helicoidal filiform winding type, designed to:

perform an efficient extraction of a product in particle form from areservoir,

be adaptable to any shape of reservoir bottom of general structure ofrevolution,

allow complete extraction of a mass of product in particle form withoutleaving a layer or cake on the bottom,

be simple, robust, reliable and require no maintenance,

require the operation of only one motorization means.

To attain the above objects, the device according to the invention, ofthe type comprising at least one extraction member, of the filiformtype, in the form of a helicoidal winding, connected at one end to amotor for driving in rotation on the general axis of said member whichextends near a support wall belonging to the reservoir, is characterizedin that this member:

is associated with means adapted to animate it in an angulardisplacement about an axis of sweep traversing the support wall,

presents at least one terminal part of filiform type extending at leastin part in a radial direction with respect to the axis of sweep,

and is obliged to cooperate with and follow the support wall during itsangular displacement.

Various other characteristics will appear from the description madehereinbelow with reference to the accompanying drawings which show, byway of nonlimiting examples, embodiments of the object of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows, in partial vertical section, a firstembodiment of the object of the invention.

FIG. 2 schematically shows in partial, vertical section a secondembodiment.

FIG. 3 schematically shows, in section from above, a third embodiment.

FIG. 4 schematically shows, in partial section, a fourth embodiment.

FIG. 5 schematically shows a partial section taken along line V--V ofFIG. 4.

FIG. 6 schematically shows in view from above, another embodiment.

BEST WAY OF CARRYING OUT THE INVENTION

FIG. 1 partly shows a storage reservoir 1 comprising a cylindricallateral wall 2 and a base or bottom 3 at the centre of which is providedan evacuation opening 4 connected to receiving devices (not shown).

The extraction device according to the invention comprises a helicoidalfiliform winding 5, of any appropriate cross-section, preferably supplein deflection, extending at least in part radially with respect to theaxis 6 of the reservoir, resting on the bottom thereof. The winding 5presents a first free terminal or distal section 5a and a second section5b connected to the proximal end of section 5a and to a motor 7 fordriving in rotation on the axis 8 of the winding. The motor 7 isassociated with means 9 for driving the winding 5 in angular sweep onthe sweeping axis 6. A cap 10, preferably conical in form, protects thedrive means 7 and 9.

Rotation of the winding 5 on its winding axis 8, combined with theangular sweeping displacement in abutment on the bottom 3, drains thematerial in particle form contained in the reservoir, in the directionof the arrow towards the opening 4, the direction of rotation of thewinding 5 on its axis being chosen to that end as a function of thedirection of the pitch of the winding.

The use of a filiform winding, of supple nature and of at least partlyradial disposition, makes it possible to effect a drive in rotationapplied at start turn after turn. The torque exerted on the powertake-off of the winding is thus established progressively, which makesit possible to employ a motor 7 whose power is less than that whichwould be necessary for driving a helicoidal member of the screw type.The progressive application of the torque also makes it possible toeliminate the risks of rupture.

The supple nature of the winding 5, which may be assimilated to ahelical spring, makes it possible, in addition, to effect an efficientextraction of the material from a bottom 3 of reservoir of anyappropriate shape. This possibility is advantageous as it allows thedevice to be used for all types of applications necessitating that thebottom 3 presents a suitable form, such as a convex, concave, conicalfunnel, etc. . .

FIG. 2 illustrates a variant embodiment in which the reservoir 1comprises a vertical tube 11 coaxial to the central axis 6 and whichopens out by an opening 4 in the form of a trumpet above the base 3,which advantageously comprises a curvilinear truncated male shape 14complementary of the opening 4. The tube 11 extends upwardly by asection 12 which emerges from the reservoir through a plate 15 removablyfixed on a lateral opening in the reservoir. The tube 11 comprises,outside the reservoir and after a more or less complicated path takinginto account the conditions of implantation, an orifice 13 forevacuation by gravity. The section of extension 12 may be supple, atleast partially.

The supple helicoidal member 5 comprises a radial sweeping part 5a, anaxial drive part 5b and an extension part 5c connected to the motor 7.

In order to take into account the extension or shortening of the winding5 as a function of its load, the bottom of the lateral wall 2 may beprovided with a peripheral horizontal housing 16 (embodiment shown onthe left-hand side of FIG. 2) or covered with a peripheral funnel-likedeflector 17 (right-hand side of FIG. 2).

The flare of the bottom of tube 11 is covered on the outside by atruncated shape 18 whose gradient is sufficient to allow natural flow ofthe product to be extracted.

The diameter of the winding 5, its pitch and the section of the wire mayvary along the winding.

The respective diameters of the winding 11 and of its extension 12 areselected to allow free rotation of the winding 5 on itself with aclearance adapted to the material in particle form. The pitch of thewinding 5, the shape and the transverse dimensions of the wireconstituting it, are adapted to the flowrate to be attained, the torqueto be transmitted and to the material in particle form.

The device operates as follows. Off-load, the winding 5 driven by themotor 7 rolls freely, at the level of its radial part 5a on the base 3,about axis 6.

Loaded, when the reservoir is filled at least partially with material inparticle form, the radial rotation of the part 5 is braked by the massof the material and is effected only as the material is levelled by eachturn of part 5a in rotation, assisted in this by its abutment on thebottom of the silo. This entrains this material towards the trumpet tube11, then, from there, through the extension 12, as far as evacuation 13.

Upon each complete turn of the base of the reservoir 1, the part 5acovers the whole of the apparent surface of the base 3 and prevents anyvaulting of the material, as the distance a from the lateral wall 2 tothe base of the tube 11, or the distance b from the bottom of the funnel17 up to the base of the tube 1, is chosen to be greater than themaximum distance of arching of the material.

A reverse device might be envisaged, consisting in causing the tube 11to emerge by the base 3 with a wall for connection to the opening 4 inthe base, preferably with curvilinear generatrix.

FIG. 3 shows a development which may be employed with the aboveembodiments. According to this development, the terminal part 5apresents an extension 5c, of length such that it is obliged to form acurved portion in the direction of angular sweep, partly abuttingagainst the peripheral wall 2. The extension 5c is of sufficient lengthfor the above condition to be respected, whatever the variations inlength of the winding as a function of the load that it undergoes andfor the radius of curvature imposed to allow rotation of the winding onitself.

Rotation of the winding 5 on itself causes screwing of the extension 5cin the mass of the material, creating, by reaction, a component oftangential force making it possible to provoke drive of the winding 5 inangular sweep around axis 6.

The length of the extension 5c, its diameter and that of the wireconstituting it, the pitch and direction of the pitch, are determined sothat, as a function of the material to be extracted, the extension 5ccan screw in the material.

The direction of rotation of the winding 5 and of the extension 5c, withrespect to the wall 2 on which it abuts, is chosen as a function of thedirection of the pitch, so that the winding 5 is obliged to applyagainst the bottom 3.

According to the development of FIGS. 4 and 5, it is advantageous toprovide, particularly but not exclusively in the event of the peripheralwall 2 defining the annular housing 16, arranging on the periphery ofthe bottom 3, a reaction element 20 adapted to cooperate with theextension 5c to promote its progression and action of drive indisplacement of the winding 5 in angular sweep of the bottom 3. Thereaction element 20 consists in a local coating offering a surface statein which the turns of the extension 5c may take and screw. A surfacestate which is particularly well suited to that end is constituted bysemi-rigid bristles, spines, barbs, fibers or loops to offer asufficient reaction to provoke the progression of the extension 5cwhilst being elastically retractable in the case of overload imposed onthe winding.

FIG. 6 shows a variant embodiment consisting in producing an extractormember by means of a helicoidal filiform winding responding to the abovecharacteristics and fitted at the end of a radial segment of rigid screw21 connected to the drive means 7 and 9 of the embodiment according toFIG. 1 for example.

INDUSTRIAL APPLICATION

The invention finds a particularly advantageous industrial applicationin the extraction of flour from reservoirs.

I claim:
 1. An extractor for removing particulate material from thebottom area of a particulate material reservoir including a peripheralwall, the extractor comprising:a helicoidal wound flexible rod sectionbeing coiled along a substantially longitudinal axis having proximal anddistal ends, and disposed so as to lie upon and extend along a bottomarea of a particulate material receptacle; drive means for driving thewound rod section in rotation about its axis of coiling connected to theproximal end only of the wound rod section; said wound rod sectionotherwise being unsupported, with the distal end of the wound rodsection disposed adjacent a peripheral wall of the receptacle; means fordriving the wound rod section to cause sweeping motion of the wound rodsection in a direction parallel to and along said bottom area, and tocause the distal end of the wound rod section to traverse the peripheralwall of the receptacle.
 2. The extractor as claimed in claim 1, whereinthe means for driving the wound rod section in a sweeping motion causestransverse sweeping motion of the wound rod section about a sweepingaxis intersecting the bottom area of the receptacle adjacent theproximal end of the wound rod section, and wherein said wound rodsection at least in part extends in a radial direction from saidsweeping axis.
 3. The extractor as claimed in claim 2, including adischarge opening for particulate material adjacent the sweeping axis.4. The extractor as claimed in claim 1, wherein said wound rod sectionincludes a distal end area abutting said peripheral wall with saiddistal end area extending along a portion of said peripheral wall, saidwound rod section being bent so that during sweeping motion the distalend of the wound rod section trails the proximal end thereof.
 5. Theextractor as claimed in claim 4, including means for at least partiallyrestraining the distal end area of the wound rod so as to require thedistal end area to remain adjacent the peripheral wall and the bottomarea of the receptacle during sweeping movement of the wound rodsection.
 6. The extractor as claimed in claim 5, wherein said means forat least partially restraining the distal end area of the wound rodsection comprises a recess in the peripheral wall of the receptacleadjacent the bottom area thereof, said distal end area of the wound rodsection disposed in said recess during its sweeping motion.
 7. Theextractor as claimed in claim 5, including reaction means adjacent themeans for restraining the distal end area of the wound rod section forengaging the distal end area of the wound rod section and causing areaction force against the wound rod section when the section is drivenrotationally about its axis of coiling, said reaction force driving saiddistal end area along the peripheral wall.
 8. The extractor as claimedin claim 7, wherein said reaction means comprises upstanding barbsarranged to engage the helical wound rod in the distal end area of thewound rod section.
 9. The extractor as claimed in claim 7, wherein saidreaction means comprises upstanding filaments arranged to engaged thehelical wound rod in the distal end area of the wound rod section. 10.The extractor as claimed in claim 7, wherein said reaction meanscomprises upstanding bristles arranged to engage the helical wound rodin the distal end area of the wound rod section.
 11. The extractor asclaimed in claim 1, including a second helically wound flexible rodsection connected to the proximal end of the first said wound rodsection, said second wound rod section connected to said drive means fortransmitting rotary motion of the drive means to said first woundsection, and a tubular conduit surrounding the second wound section andterminating at one end adjacent the proximal end of the first woundsection and at another end outside the container, whereby said tubularconduit receives particulate material moved towards the proximal end ofthe first wound rod section when the first wound rod section is drivenin rotation, and wherein said tubular conduit and said second wound rodsection constitute a conveyor for moving particulate material out of thecontainer when the second wound rod section is rotated within saidtubular conduit.